Stewart Corman
29th March 2007, 19:57
I have organized a series of my photos showing some novel shop techniques that I have developed.
The actual prototype blades are non twist/tapered NACA4425 and are 48inches long mounted on 14 inch heavy tubing spars to produce a 10ft+ turbine. Max thickness at root is 2 1/4" x 9" cord and tip is 3/4" x 3" cord.
When assembling rotor, tubing is clamped onto mounting plate by three exhaust clamps, allowing for unlimited fixed pitch angle setpoints. BTW, all the wood you see is scrap from my shop and the cost of the steel tubing was $0.50 for 5 foot lengths which produced (3) 20 inch sections as required. Not counting cost of sandpaper or electric tool power, the only other cost was $1/blade for Minwax exterior spar polyurethane for three coats. I will provide footnotes for each picture
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4200.jpg
strips of wood 2 1/2 " thick x 48 inches long were glued up to a total thickness of 10 inches ...outside strips were either maple or cherry
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4201.jpg
note that besides pipe clamps, "C" edge clamps align vertical edges
Titebond III glue is waterproof and sets in an hour
note also the finished stock in back with diagonal line drawn ..each layup makes two blades by cutting with bandsaw
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4238.jpg
horizontal boring is done with 1 1/4" spade bit (fitted into 1/2 shafting to add distance and stiffness) for snug fit to tubing
stops/clamps are used for reproducibility ..this setup allows for "swept wing" mounting if desired by angling the stops
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4241.jpg
note spade bit fitted into 1/2 shafting to add distance and stiffness
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4251.jpg
after jointing the saw kerf, a smaller piece of hardwood is glued to the bottom of each trailing edge ...this way grain is parallel to finished blade
to be continued
The actual prototype blades are non twist/tapered NACA4425 and are 48inches long mounted on 14 inch heavy tubing spars to produce a 10ft+ turbine. Max thickness at root is 2 1/4" x 9" cord and tip is 3/4" x 3" cord.
When assembling rotor, tubing is clamped onto mounting plate by three exhaust clamps, allowing for unlimited fixed pitch angle setpoints. BTW, all the wood you see is scrap from my shop and the cost of the steel tubing was $0.50 for 5 foot lengths which produced (3) 20 inch sections as required. Not counting cost of sandpaper or electric tool power, the only other cost was $1/blade for Minwax exterior spar polyurethane for three coats. I will provide footnotes for each picture
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4200.jpg
strips of wood 2 1/2 " thick x 48 inches long were glued up to a total thickness of 10 inches ...outside strips were either maple or cherry
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4201.jpg
note that besides pipe clamps, "C" edge clamps align vertical edges
Titebond III glue is waterproof and sets in an hour
note also the finished stock in back with diagonal line drawn ..each layup makes two blades by cutting with bandsaw
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4238.jpg
horizontal boring is done with 1 1/4" spade bit (fitted into 1/2 shafting to add distance and stiffness) for snug fit to tubing
stops/clamps are used for reproducibility ..this setup allows for "swept wing" mounting if desired by angling the stops
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4241.jpg
note spade bit fitted into 1/2 shafting to add distance and stiffness
http://i145.photobucket.com/albums/r203/scorman1/Turbine%20project/blade%20construction/4251.jpg
after jointing the saw kerf, a smaller piece of hardwood is glued to the bottom of each trailing edge ...this way grain is parallel to finished blade
to be continued